Tech to Watch: Energy Storage

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Joe Piccirilli is convinced that in the next few years, nearly every house will have some form of energy storage.

Piccirilli is the managing director of RoseWater Energy Group, which is rolling out a Model 1012 Residential Energy Storage Hub that stores energy from a solar photovoltaic (PV) array or a standby generator, so a home can power itself in the event of a power outage or help the local utility shed loads during peak usage periods.

“I really do think that in less than a decade [residential power storage] will be as common as a dishwasher,” Piccirilli says.

His reasoning? Electric utilities want to “even out” their loads by reducing the amount of energy used during “peak load” periods like afternoons and prime time, while increasing the amount of energy used at night. That’s why utilities are testing and deploying Demand Response (DR) programs that provide incentives to homeowners who agree to have the utility power down their big energy users like air conditioning systems during peak load periods.

Power to the Utility, Power to the Builder

RoseWater’s Residential Energy Storage Hub is really an uninterruptible power supply (UPS, kind of like the one you’d use next to your home office setup, only on a much larger scale.

With an adequate energy storage system, says Piccirilli, a house can pull itself completely off the grid during these peak usage times—and if enough houses do that, the utility has a much better chance of matching its output to demand, thereby evening that load and running much more efficiently.

This is something utilities love to see.”

RoseWater has commissioned a Queen’s University study in Ontario that Piccirilli says shows how residential power storage can shave peak loads and offset a utility’s capital expenditures. Which means power storage systems like RoseWater’s can be worth money to utilities.

And what does that mean to homebuilders? “This is something utilities love to see,” he says. “If you build 300 homes with these, you’re not going to stress out the grid. Utilities love this sort of thing.”

Not Your Average Battery Pack

The Residential Energy Storage Hub is no dishwasher-size unit. The Hub is a locker-size 24 inches wide by 36 inched deep by 72 inched tall, and contains 24 storage batteries, a solar inverter, and and a dual power conversion and stabilization process that provides whole-house power protection for home electronics and other systems. “We convert all power to DC, stabilize it, and convert it back to AC to guarantee pure sine wave, constant 110v/60Hz power.” says Piccirilli.

Each system can store power from up to a 10-kw solar array or a generator. An Energy Router contained in the unit has the software to track energy loads and sources and route energy to your selected circuits. There’s also a display control panel, automatic transfer switch with manual bypass, a main input circuit breaker, and an anti-islanding relay to prevent back-feeding to the grid.

An original system showed last year was about twice as large in size, due to the use of bulky lead carbon batteries. Now the system is battery-agnostic, using smaller and more compact lithium ion or GE Durathon batteries that use sodium metal halide chemistry and nickel chloride (metal salt technology) for greater energy density.

The 12 kwH of storage can power a house for the better part of a day using 2 kw of electricity each hour, says Piccirilli.

All of a sudden you're going to see huge volumes, and you’ll see prices plummet.”

The cost for a RoseWater Energy Storage Hub? Try a cool $60,000. Though as Piccirilli reminds us, many technologies when they start out are expensive and more exclusive to the high end before experiencing rapid price declines as volume rises.

The battery market in particular, he says, has been centered on how the car industry goes. “As we get into non-automotive applications like data centers and the millions of households in United States, cottages and RVs and third world countries that want products like this, all of a sudden you're going to see huge volumes and you’ll see prices plummet, probably within three to five years.”

Battery technology is also advancing to the point where we may see solid-state batteries using rare earth minerals and fuel cells, possibly even powered by hydrogen.

EVs and Energy Storage

Energy storage in the home is likely to gain prominence as electric vehicles (EVs) come into vogue. EV charging can put tremendous strains on local transformers and the grid, particularly if many people plug in their cars to charge at the same time. “Smart charging” EVs at night and variable Time of Use rates introduced by electric utilities will be aimed, again, at evening those utilities loads. Here again, home energy storage can help.

RoseWater is toying with projects that may add a second battery pack for direct EV charging from the batteries. Piccirilli says the company is also playing with the idea of setting set up its box to sell power back to the grid.